565f13088f
Change the kernel to add features to vircopy and safecopies so that
transparent copy fixing won't happen to avoid deadlocks, and such copies
fail with EFAULT.
Transparently making copying work from filesystems (as normally done by
the kernel & VM when copying fails because of missing/readonly memory)
is problematic as it can happen that, for file-mapped ranges, that that
same filesystem that is blocked on the copy request is needed to satisfy
the memory range, leading to deadlock. Dito for VFS itself, if done with
a blocking call.
This change makes the copying done from a filesystem fail in such cases
with EFAULT by VFS adding the CPF_TRY flag to the grants. If a FS call
fails with EFAULT, VFS will then request the range to be made available
to VM after the FS is unblocked, allowing it to be used to satisfy the
range if need be in another VFS thread.
Similarly, for datacopies that VFS itself does, it uses the failable
vircopy variant and callers use a wrapper that talk to VM if necessary
to get the copy to work.
. kernel: add CPF_TRY flag to safecopies
. kernel: only request writable ranges to VM for the
target buffer when copying fails
. do copying in VFS TRY-first
. some fixes in VM to build SANITYCHECK mode
. add regression test for the cases where
- a FS system call needs memory mapped in a process that the
FS itself must map.
- such a range covers more than one file-mapped region.
. add 'try' mode to vircopy, physcopy
. add flags field to copy kernel call messages
. if CP_FLAG_TRY is set, do not transparently try
to fix memory ranges
. for use by VFS when accessing user buffers to avoid
deadlock
. remove some obsolete backwards compatability assignments
. VFS: let thread scheduling work for VM requests too
Allows VFS to make calls to VM while suspending and resuming
the currently running thread. Does currently not work for the
main thread.
. VM: add fix memory range call for use by VFS
Change-Id: I295794269cea51a3163519a9cfe5901301d90b32
42 lines
927 B
C
42 lines
927 B
C
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#include <minix/sys_config.h>
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#include <minix/type.h>
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#include <minix/param.h>
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#include <sys/stat.h>
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#include "vm.h"
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#include "vmproc.h"
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#if _MAIN
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#undef EXTERN
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#define EXTERN
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#endif
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#define VMP_EXECTMP _NR_PROCS
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#define VMP_NR _NR_PROCS+1
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EXTERN struct vmproc vmproc[VMP_NR];
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long enable_filemap;
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EXTERN kinfo_t kernel_boot_info;
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#if SANITYCHECKS
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EXTERN int nocheck;
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EXTERN int incheck;
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EXTERN int sc_lastline;
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EXTERN const char *sc_lastfile;
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#endif
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extern struct minix_kerninfo *_minix_kerninfo;
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/* mem types */
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EXTERN mem_type_t mem_type_anon, /* anonymous memory */
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mem_type_directphys, /* direct physical mapping memory */
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mem_type_anon_contig, /* physically contig anon memory */
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mem_type_cache, /* disk cache */
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mem_type_mappedfile, /* memory with file contents */
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mem_type_shared; /* memory shared by multiple processes */
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/* total number of memory pages */
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EXTERN int total_pages;
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